Temperature and power supply compensation circuit for integrated circuits
First Claim
1. In an electronic circuit having a monolithic integrated circuit with at least one integrated resistor with a first temperature coefficient and having a resistor external to said integrated circuit with a second temperature coefficient different from said first temperature coefficient, the improvement comprising an integrated bias circuit for deriving a current from said external resistor which current is compensated for temperature-induced changes in the value of said integrated resistor, said bias circuit comprisingmeans for passing a current which varies with said temperature-induced changes in the value of said integrated resistor through said integrated resistor to develop a voltage which is independent of said temperature induced changes in the value of said integrated resistor,means for sensing said voltage developed across said integrated resistor, andmeans for producing a voltage across said external resistor which is proportional to said voltage developed across said integrated resistor.
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Abstract
A monolithic integrated circuit generates a programmable time delay under control of a digital work. The delay is generated by comparing a ramp signal to a threshold determined by the value of the digital word and appears as a time difference between a trigger pulse and a pulse generated when the value of the ramp voltage equals the value of the threshold voltage. The ramp voltage is generated by a simple resistance/capacitance charging circuit whose time constant can be adjusted by the user. The threshold voltage is set by a digital-to-analog converter (DAC) and resistor circuit which converts the digital control word into a variable voltage. In order to stabilize the device against changes in temperature and power supply variations, a voltage coupling circuit forces the threshold voltage to track changes in the ramp voltage caused by temperature and power supply variations. The coupling circuit obviates the need for percision voltage sources or current mirrors conventionally used to compensate for temperature and power supply changes. Without the need for the latter device, the integrated circuit can be easily and inexpensively fabricated of transistors of a single bipolar type.
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Citations
16 Claims
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1. In an electronic circuit having a monolithic integrated circuit with at least one integrated resistor with a first temperature coefficient and having a resistor external to said integrated circuit with a second temperature coefficient different from said first temperature coefficient, the improvement comprising an integrated bias circuit for deriving a current from said external resistor which current is compensated for temperature-induced changes in the value of said integrated resistor, said bias circuit comprising
means for passing a current which varies with said temperature-induced changes in the value of said integrated resistor through said integrated resistor to develop a voltage which is independent of said temperature induced changes in the value of said integrated resistor, means for sensing said voltage developed across said integrated resistor, and means for producing a voltage across said external resistor which is proportional to said voltage developed across said integrated resistor.
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9. In an electronic circuit having a monolithic integrated circuit with at least one integrated resistor with a first temperature coefficient and having a resistor external to said integrated circuit with a second temperature coefficient different from said first temperature coefficient, the improvement comprising an integrated bias circuit for deriving a current from said external resistor which current is compensated for temperature-induced changes in the value of said integrated resistor, said bias circuit comprising
means for passing a current through said integrated resistor to develop a voltage, means for sensing said voltage developed across said integrated resistor, and means for producing a voltage across said external resistor which is proportional to said voltage developed across said integrated resistor wherein said producing means comprises a first transistor and a second transistor, each having base and collector leads, the base of said first transistor being coupled to the collector of said second transistor and the base of said second transistor being coupled to the collector of said first transistor.
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16. A monolithic integrated electronic circuit for deriving a current which is compensated for temperature-induced changes in said integrated circuit from a resistor having a first temperature coefficient, said integrated circuit comprising:
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at least one integrated resistor with a second temperature coefficient different from said first temperature coefficient, means for passing a current through said integrated resistor to develop a voltage, means for sensing said voltage developed across said integrated resistor, and means for producing a voltage across said external resistor which is proportional to said voltage developed across said integrated resistor wherein said producing means comprises a first transistor and a second transistor, each having base and collector leads, the base of said first transistor being coupled to the collector of said second transistor and the base of said second transistor being coupled to the collector of said first transistor.
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Specification